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Old March 3rd, 2014, 09:57 AM   #1
Charbel
Member
Lebanon

Charbel is offline
 
Join Date: Jan 2012
Location: Beirut
Posts: 284
Control based on level and VSD

Dear,

there was a requirement to control the variable speed pumps based on level and at the same time change their speed.
The system consists of 2 pumps, please see picture below.

See the sequence of operation:

L1 is the level of dry run protection for the pumps at which low low level alarm shall be activated
At L3, pump 1 shall start.
During operation i.e. between level 2 and level 3, the speed of the pump is controlled by the level of sewage as measured by the hydrostatic level sensor such that when the level of sewage is increased after a predefined time, the speed of the pump shall be increased to cater for the increase of the sewage incoming flow
During operation i.e. between level 2 and level 3, when the level of sewage is decreased after a predefined time, the speed of the pump shall be decreased to cater for the decrease of sewage incoming flow.
When the first pump reaches full speed and sewage level reaches L4, the second pump shall cut in and an high high level alarm shall be activated, both pumps shall start running at the same speed to cater for the required demand.
Do you have feedback on the above, is the system workable from hydraulical point of view and is it easy to program?

thanks a lot for your valuable feedback!
Attached Images
File Type: jpg vsd transfer pumps set.jpg (12.8 KB, 78 views)
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